IN-24-A007 - Retrofitting Application of EC Motor Plug Fans in HVAC systems

This study focuses on an electrically commutated (EC) motor with a direct-driven plug fan in the application of HVAC systems. In recent years, the improvement of permanent magnet motors in efficiency and reliability has urged to replace the traditional AC motor with an EC fan. Many HVAC projects have started to retrofit the AC motor belt-driven centrifugal fan with housing into the EC fan. To compare EC fans' performance and benefits to AC fans, this study experiments and field measurement on two retrofit projects. The performance rating is based on AMCA 207 standards, including transmission loss, motor efficiency, driver efficiency, and fan efficiency based on the AMCA certification. In the retrofitting project, the error for the efficiency evaluation method and field measurement is within 5%, which proves that the evaluation could be applied. Case 1 is a fan retrofit project of AHU in the airport waiting room. The overall efficiency of the original AC fan is 51%, and the EC fan is 66%, which results in 23% full load energy saving. In Case 2, a primary AHU retrofit project in a hospital, the overall efficiency of a 10% AC fan was replaced with a 42% EC fan. Both cases show significant potential for energy saving.